The invention relates to organic inhibitor treating solutions and a method for using such solutions to reduce corrosion from the harsh fluid environments encountered in the oil field. More particularly, the invention concerns treating solutions containing the reaction product of a dione and a primary polyamine. Such solutions are effective in reducing sweet and sour corrosion.
Corrosion that occurs in an oil field environment is extremely complex and tends to attack all manner of metal equipment above and below ground. The principle corrosive agents found in the well fluids include hydrogen sulfide, carbon dioxide, oxygen, organic acids and solubilized salts. These agents may be present individually or in combination with each other. Valves, fittings, tubing, pumps, precipitators, pipelines, sucker rods, and other producing equipment are particularly susceptible. Deposits of rust, scale, corrosion byproducts, paraffin and other substances create ideal environments for concentration cells. Carbon dioxide and hydrogen sulfide induced pitting is encouraged by such deposits. Acidic condensate that collects on metal tubing will also cause pitting. Extreme temperatures and pressures in downhole environments further accelerate corrosion.
Very often as oil fields mature and enhanced recovery methods such as water flooding and miscible flooding are instituted, the concentrations of hydrogen sulfide and carbon dioxide in the well fluids increases dramatically. This increase in concentration and the resultant increase in sweet corrosion or sour corrosion may make older oil fields economically unattractive due to excessive corrosion costs.
Amines and ethoxylated amines of various structures have been employed in corrosion inhibition systems. U.S. Pat. No. 2,466,517 provides one example. U.S. Pat. Nos. 2,485,309; 2,496,354; 2,514,508; 2,596,273 and 2,596,425 disclose corrosion control use of reaction products of selected amines and formaldehyde, chiefly methylol melamine.